Benadryl vs. Olanzapine


We compare the side effects and drug effectiveness of Benadryl and Olanzapine. The study is created by eHealthMe based on reports of 181,056 people who take Benadryl and Olanzapine, and is updated regularly.

What's eHealthMe?

eHealthMe is a health data analysis company based in Mountain View, California. eHealthMe monitors and analyzes the outcomes of drugs and supplements that are currently on the market. The results are readily available to health care professionals and consumers.

eHealthMe has released original studies on market drugs and worked with leading universities and institutions such as IBM, London Health Science Centre, Mayo Clinic, Northwestern University and VA. eHealthMe studies have now been referenced in over 500 peer-reviewed medical publications.

How we gather our data?

Healthcare data is obtained from a number of sources including the Food and Drug Administration (FDA). This information is aggregated and used to produce personalized reports that patients can reference.

The information that eHealthMe collects includes:

  • Side effects (including severity and how people recover from them)
  • Associated conditions or symptoms
  • Drug effectiveness
  • Demographic data regarding drug use

How the study uses the data?

The study is based on diphenhydramine hydrochloride and olanzapine (the active ingredients of Benadryl and Olanzapine, respectively). Other drugs that have the same active ingredients (e.g. generic drugs or brand names) are also considered.

What is Benadryl?

Benadryl has active ingredients of diphenhydramine hydrochloride. It is often used in allergies. (latest outcomes from Benadryl 57,530 users)

What is Olanzapine?

Olanzapine has active ingredients of olanzapine. It is often used in bipolar disorder. (latest outcomes from Olanzapine 30,526 users)

How to use the study?

Patients can bring a copy of the report to their healthcare provider to ensure that all drug risks and benefits are fully discussed and understood. It is recommended that patients use the information presented as a part of a broader decision-making process.

On Feb, 28, 2019

181,056 people who take Benadryl and Olanzapine are studied.

Number of reports submitted per year:

Benadryl vs Olanzapine drug comparison reports.

Drugs in this study:

  • Benadryl (diphenhydramine hydrochloride)
  • Olanzapine (olanzapine)

Most common side effects:

  1. Diabetes Mellitus (diabetes, caused by a deficiency of the pancreatic hormone insulin)
  2. Weight Increased
  3. Overdose
  4. Drug Ineffective
  5. Anxiety
  6. Somnolence (a state of near-sleep, a strong desire for sleep)
  7. Pyrexia (fever)
  8. Agitation (state of anxiety or nervous excitement)
  9. Pancreatitis (inflammation of pancreas)
  10. Hypertension (high blood pressure)
  1. Nausea (feeling of having an urge to vomit)
  2. Dyspnoea (difficult or laboured respiration)
  3. Fatigue (feeling of tiredness)
  4. Headache (pain in head)
  5. Pain
  6. Vomiting
  7. Diarrhoea
  8. Pyrexia (fever)
  9. Rash
  10. Drug Ineffective

Most common side effects experienced by people in long term use:

  1. Diabetes Mellitus (diabetes, caused by a deficiency of the pancreatic hormone insulin)
  2. Weight Increased
  3. Pancreatitis (inflammation of pancreas)
  4. Hypertension (high blood pressure)
  5. Hyperglycaemia (high blood sugar)
  6. Type 2 Diabetes Mellitus
  7. Blood Triglycerides Increased
  8. Obesity (a medical condition in which excess body fat)
  9. Blood Cholesterol Increased
  10. Diabetic Ketoacidosis (diabetic ketoacidosis (dka) is high concentrations of ketone bodies)
  1. Drug Ineffective
  2. Weight Decreased
  3. Infusion Related Reaction
  4. Rheumatoid Arthritis (a chronic progressive disease causing inflammation in the joints)
  5. Headache (pain in head)
  6. Arthralgia (joint pain)
  7. Fatigue (feeling of tiredness)
  8. Pain
  9. Nausea (feeling of having an urge to vomit)
  10. Blood Pressure Increased

Drug effectiveness:

  • not at all: 8.47 %
  • somewhat: 26.03 %
  • moderate: 32.08 %
  • high: 23.49 %
  • very high: 9.93 %
  • not at all: 3.25 %
  • somewhat: 24.9 %
  • moderate: 35.8 %
  • high: 26.73 %
  • very high: 9.32 %

Do you take Benadryl or Olanzapine?

You are not alone:

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Compare Olanzapine with similar drugs

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WARNING: Please DO NOT STOP MEDICATIONS without first consulting a physician since doing so could be hazardous to your health.

DISCLAIMER: All material available on is for informational purposes only, and is not a substitute for medical advice, diagnosis, or treatment provided by a qualified healthcare provider. All information is observation-only, and has not been supported by scientific studies or clinical trials unless otherwise stated. Different individuals may respond to medication in different ways. Every effort has been made to ensure that all information is accurate, up-to-date, and complete, but no guarantee is made to that effect. The use of the eHealthMe site and its content is at your own risk.

You may report adverse side effects to the FDA at or 1-800-FDA-1088 (1-800-332-1088).

If you use this eHealthMe study on publication, please acknowledge it with a citation: study title, URL, accessed date.